Design of flange lugs 1

[orlandini]

Colleagues,
to design a base plate for a top flange lug, I want to use formulas for flat circular plates of constant thickness of Roark’s Formulas for Stress and Strain Ed. VII.
Which condition I need to considerer for this calculation: edge simply supported (like cases 16 and 20 of Roark Ed. VII – Table 11.2) or edge fixed (like cases 17 and 21 of Roark Ed. VII – Table 11.2)?

Regards....

 

[racookpe1978]

What are calling the flange "base plate"? Aren't you going to specify a standard flange size, thickness, material and bolt pattern so you can use a standard pipe mating piece?

Pressure? Temperature? Service use? Fluid? Tank material?

 

[lganga]

The situation of a welded flat head is close to edge fixed.
You can look ata ASME VII 1 or many soft for pressure vessel design.
It is a good practice to read a lot about what has been already done about your questions.
Please follow that way to get better profit
Regards
Luis

 

[orlandini]

Excuse me for not explaining right.
I want to calculate the blind cover of a lifting lug to use for lifting a vessel. The blind cover is bolted to a top vessel flange. I need to know which condition I have to use: edge simply supported or edge fixed as boundary conditions for my model.

 

[bernoullies123]

Sorry, don't have my copy of Roark's handy, but here are some figures you can cross check against ...

Table 7-9 Pressure Vessel Design Manual, 3rd ed. by Dennis Moss
Load Capacity (tons) / flange base plate thickness
50 / 2
100 / 3
200 / 4
400 / 5
600 / 6
800 / 7

The design of the Lug Base Plate is per Roark, 4th Edition Table III, Case 34.

Remember to check your actual nozzle/flange/shell stresses.